Sometimes it is cloudy at noon, so that he can't look at the sun then, but it clears up after dark. Then the captain looks through his sextant at the moon, or at some bright star, and finds his position that way. And sometimes it is cloudy for several days together, so that he can't take an observation with his sextant in all that time. Captains don't like it very well when it is cloudy for several days together, for then they have nothing to tell them just where the ship is, but what is called "dead reckoning."

Captain Solomon usually had the speed at which the ship was sailing measured several times every day. When he wanted that done, he called a sailor to "heave the log;" and the sailor came and took up a real log, or board, fastened to the end of a long rope, while one of the mates held an hour glass. But there wasn't sand enough in the glass to run for an hour, but it would run for half a minute. And when the mate gave the word, the sailor dropped the log over the stern of the ship and the mate turned the glass. And the sailor held the reel with the rope on it, so that the rope would run off freely, and he counted, aloud, the knots in the rope as it ran out. For the rope had knots of colored leather in it, and the knots were just far enough apart so that the number of knots that ran out in half a minute would show the number of sea miles that the ship was sailing in an hour. And when the sand in the glass had all run out, the mate gave the word again, and the sailor stopped the rope from running out. So Captain Solomon knew about how many miles the Industry had sailed on each course, and he could put it down in his book.

That wasn't a very good way to tell where the ship was, by adding up all the courses she had sailed and getting her speed on each course, and adding all these to the last place that they knew about, but, when Captain Solomon couldn't get an observation with his sextant, it was the only way there was. That isn't the way they tell, now-a-days, how many miles a ship has sailed, for there is a better way that gives, more exactly than the old-fashioned "log," the number of miles. But they still have to add up all the courses and the miles sailed on each course to find a ship's place, when they can't take an observation. That is what is called "dead reckoning," and it isn't a very good way at its best.

Little Jacob liked to watch Captain Solomon writing up the log for the day. He always wrote it just after dinner. And when he had finished dinner, he would get out the book and clear a place on the table to put it; and then he took a quill pen in his great fist and wrote, very slowly, and with flourishes. And when he had it done he always passed the book over to little Jacob.

"There, Jacob," he said, with a smile. "That please you?"

"Oh, yes, sir," answered little Jacob. "Thank you, sir." And he began to read.

One day, when they had been out of Boston about three weeks, little Jacob watched Captain Solomon write up the log, and, when he got it, he thought he would turn back to some days that he knew about and read what Captain Solomon had said about them. And so he did.

That didn't seem to little Jacob to be enough to say about the porpoises. He sighed and turned to another day.

And it seemed to little Jacob that it was a shame to say no more than that about that strange Seaweed Sea and the curious things that were to be found in it. But it was Captain Solomon's log and not little Jacob's. He turned to another day, to see what there was about the flying fish.

Little Jacob didn't know what Spica and Aquila were, and he asked Captain Solomon.

"They are stars, Jacob, and rather bright ones," said Captain Solomon. "My chronometer—my clock, you know—was losing a good deal, and I looked through my sextant at them to find out where we really were."

"Oh," said little Jacob; but he didn't understand very well, and Captain Solomon saw that he didn't. It wasn't strange that he didn't understand.

Little Jacob sat looking at the log book and he didn't say anything for a long time.

Captain Solomon smiled. "Well, Jacob," he said, at last, "what are you thinking about? I guess you were thinking that you wished that you had the log to write up. Then you could say more about the things that were interesting. Weren't you?"

Little Jacob got very red. "Oh, no, sir," he said. "That is, I—well, you see, the things that are new and interesting to me—well, I s'pose you have seen them so many times that it doesn't seem worth while to you to say much about them."

"That is a part of the reason," answered Captain Solomon. "The other part is that it doesn't seem necessary. Anything that concerns the ship is put down. We don't have time—nor we don't have the wish—to put down anything else."

"Of course," said little Jacob, "it isn't necessary."

"I'll tell you what I'll do, Jacob," said Captain Solomon. "I'll let you write up the log, and then you can write as much as you like about anything that interests you."

Little Jacob got very red again. "Oh!" he cried, getting up in his excitement. "Will you let me do that? Thank you. I thank you very much. But—but how shall I put down all those numbers that show how the ship goes?"

"I'll give you the numbers, as you call them," said Captain Solomon, "and I'll look over the log every day, to see that you put them down right."

"I'll put them down just exactly the way you tell me to," said little Jacob. "And I thank you very much. And I—I write pretty well."

And little Jacob ran to find little Sol and to tell him about how he was going to write the log of the voyage, after that. And he did write it, numbers and all, and it was a very interesting and well written log. For little Jacob could write very well indeed; rather better than Captain Solomon. Captain Solomon knew that when he said that little Jacob could write it.

And that's all.